Rotors for thermal turbomachines such as axial compressors and gas turbines are known in different designs from the comprehensively available prior art. For example, welded rotors are known for gas turbines, in the case of which welded rotors drums of different width are welded to one another to form a monolithic rotor. Secondly, it is known to stack a plurality of disk-shaped elements (also known as rotor disks) and to brace them with the aid of one or more tie rods to form a fixed structure. Even combinations of said designs are known. Rotor blades are mounted on the outside of all rotors, which rotor blades can be assigned in the case of gas turbines, for example, either to the compressor or to the turbine unit. Regardless of the design, a medium can be introduced into the interior of the rotors via holes which are arranged in the rotor shell, in order to conduct said medium from the feed position to a second axial position, where the medium is removed from the rotor again. This method is used, in particular, in gas turbines, in order to remove cooling air from the main flow path of the compressor of a gas turbine on the rotor side and to conduct it to the turbine unit, where, guided out of the rotor interior again, it can be used for cooling air purposes and/or sealing air purposes.
In order to make an aerodynamically efficient removal of air from the compressor of a gas turbine and efficient conducting of the air in the rotor interior possible, different constructions are known.
The aim here is first of all to guide the cooling air out of the flow path in the compressor to the rotor interior. To this end, removal holes are as a rule arranged in at least one rotor disk of the compressor, which removal holes in the simplest case run through the rotor disk radially perpendicularly with respect to the rotor axis. As an alternative to this, embodiments are known, for example from DE 198 52 604 A1, in which the removal hole is arranged in the rotor disk in an inclined manner with respect to the radial direction, the cooling air being removed from an upstream side upstream of the compressor blades which are arranged on the rotor disk and exiting out of the rotor disk in the interior of the rotor again on a downstream side close to the rotor axis.
By means of the cooling air from the main flow path being conducted through the rotor disk, the temperature control of the rotor disk is improved and a thermal equilibrium is achieved more rapidly.
Although the known cooling air routing through the rotor disk provides a suitable solution for cooling air routing and at the same time for the temperature control of the rotor disk, there is nevertheless the requirement to make the cooling air routing more effective on account of a general performance increase in gas turbines.